This invention relates generally to apparatus for indicating the location of the drill bit at the bottom of a well bore and in particular to apparatus for generating a sonic signal at the drill bit which can be detected at the surface in a manner to permit calculation of the location of the drill bit.
It is desirable for a driller to know at all times the location of the low side of the hole. Previously known methods for providing such information include placing complex mechanical and electronic equipment in the bore hole, usually just above the drill bit, and sending electrical information back through wires, or sonic information along the drill pipe or through the drilling mud. The rotation of the drill stem and the harsh environment combine to make these previously known methods generally unsatisfactory. Photographic recording of borehole data has also been investigated but recovery of the acquired information is slow and costly due to the effort involved in pulling the bit out of the hole to recover the exposed film.